Trigger mechanism for power tool

ABSTRACT

A trigger mechanism for operating a power tool which may be assembled for &#39;&#39;&#39;&#39;Lock-Out&#39;&#39;&#39;&#39; operation to prevent accidental operation of the tool or for a &#39;&#39;&#39;&#39;Lock-In&#39;&#39;&#39;&#39; operation for continuous operation of the tool. The trigger mechanism includes a movable trigger which operates an electrical switch and a control pin which controls movement of the trigger in operation of the switch.

0 United States Patent [151 3,662,136 Bienwald et al. Ma 9 197 2 [5 TRIGGER MECHANISM FOR POWER References Cited TOOL UNITED STATES PATENTS [72] Inventors; W lfgang Bienwald Huntington 3,356,814 12/ 1967 France ..200/157 tion; J. Bowie, Bethpage, h f Sorenson X N.Y.

Primary Examiner-H. 0. Jones [73] Assignee: Leviton Manufacturing Co., Inc., Assistant Examiner-M. Ginsburg Brooklyn, NY. Alt0rneyHanse H. Hamilton [22] Filed: May 20, 1971 57 ABSTRACT PP 145,124 A trigger mechanism for operating a power tool which may be assembled for Lock-Out operation to prevent accidental operation of the tool or for a Lock-In" operation for continu- [52] US. Cl. ..200/157, 200/ l 69 PB ous operation ofthe tool. [51] Int. Cl. ..H01h 13/02 58 Field of Search ..200/157 169 PB The mechamsm Includes whlch operates an electrical switch and a control pin which controls movement of the trigger in operation of the switch.

9 Claims, 16 Drawing Figures E! l J V i 27% A LII/I ll PATENTEBMAY 91912 SHEET 1 OF 2 VIZ INVENTORS wzrewwfi EA/W440 mum/J dW/E ATTORNEY PATENTEUMAY 9 I972 SHEET 2 BF 2 ,4 1754/14 40 5- 'FdW/E INVENTORS ATTO R N EY TRIGGER MECHANISM FOR POWER TOOL The present invention relates to a trigger mechanism for controlling the operation of a power tool.

It relates, more particularly, to a trigger mechanism for operating an electric switch which control operation of a power tool.

An object of the present invention is to provide a trigger mechanism which can be assembled for either a Lock-Out operation or a Lock-In operation of a power tool.

A trigger mechanism embodying the invention provides different modes of operation; i.e., Lock-Out or Lock-In" modes depending upon the manner in which the trigger mechanism is assembled, but with the same parts being utilized.

As used herein, the term Lock-Out means that the trigger is secured against unintentional operation or actuation of the tool. This provides an important safety factor where, as for example, operation of the tool is temporarily interrupted for movement from one location to another but remains connected to the source of power.

The term Lock-In" means that the trigger mechanism maintains the tool in a continuous operation for as long as desired or until the trigger is intentionally released for movement to interrupt operation of the tool. This type of operation is customarily used in power tools such as drills.

A feature of the invention is that the same parts may be employed in the trigger mechanism for both modes of operation or control of the power tool. The particular mode of operation selected will dictate how the trigger mechanism is to be assembled and this will not be subject to change after the selection has been made.

Other objects and advantages of the present invention will be better understood from the following description and the accompanying drawings in which:

FIG. 1 is a side view of a trigger mechanism embodying the present invention which is assembled for a lock-out mode of operation;

FIG. 2 is a plan view of the trigger mechanism shown in FIG. 1 in section taken along line 2-2 of FIG. 1;

FIG. 3 is a fragmentary view in section taken along line 3-3 of FIG. 2;

FIG. 4 is a fragmentary view in section taken of FIG. 2;

FIG. 5 is a fragmentary view in section which corresponds to FIG. 2 with certain parts being omitted and with the trigger mechanism in a different position;

FIG. 6 is a fragmentary view in section which corresponds to FIGS. 2 and 5, with certain parts being omitted and with the trigger mechanism in another position;

FIG. 7 is a fragmentary view in section taken along line 7-7 of FIG. 6;

FIG. 8 is a fragmentary view in section of a portion of the trigger mechanism shown in FIGS. 1 and 2;

FIG. 9 is a fragmentary view in section taken of FIG. 8;

FIG. 10 is a perspective view in partial section illustrating a trigger and a control member for the trigger mechanism shown in FIG. 1;

FIG. 11 is a fragmentary view in section of the trigger mechanism which corresponds to FIG. 2, but with the parts of the trigger mechanism assembled for a different mode of operation;

FIG. 12 is a fragmentary view in section of the trigger mechanism shown in FIG. 11, but with the parts in a different operating position;

FIG. 13 is a fragmentary view in section taken along line 13-13 ofFIG. 11;

FIG. 14 is a fragmentary view in section taken along line 14-14 ofFIG.12;

FIG. 15 is a side view of a modified form of latch and control pin; and

FIG. 16 is a fragmentary view in partial section of the assembly shown in FIG. l2 with the modified form of latch shown in FIG. 15.

along line 4-4 along line 99 Referring now to the drawings in detail, there is a trigger mechanism 20 for operating a power tool (not shown).

The trigger mechanism includes a trigger 21 which is movable in operation of an electric switch 22 to establish or interrupt a circuit connecting a power tool such as a circular saw or the like to a source of a-c power.

The switch 22 may be of conventional construction and operation and hence, need not be described in detail here. An example of such a switch and its operation is shown and described in our copending US. application Ser. No. 61,376 filed Aug. 5, 1970, entitled Tease-Proof Electric Switch and reference may be made thereto in connection with the subject application.

The trigger 21 is slidably mounted in a housing 23 which may be attached to the tool. The trigger 21 is movable between a retracted or off position, as shown in FIG. 1, and a depressed or on" position as shown in FIG. 6. The housing 23 has an open rear end into which the front or forward end of the trigger 21 fits and a coil spring 24 which is interposed between the forward end of the trigger 21 and the forward end of the housing 23, urges the trigger 21 rearwardly or to its off position relative to the housing. Normally, the trigger 21 when released by the operator returns to the off position under the influence of the spring 24 and the switch 22 interrupts the circuit to the tool. As will be described, the return movement of the trigger does not take place until the trigger is released from its full on position.

In the assembly shown in FIGS. l-9, the trigger mechanism 20 functions in the Lock-Out mode of operation. When assembled in this manner, the trigger 21 cannot be depressed accidentally to operate the switch and close the circuit to actuate the tool.

In the assembly shown in FIGS. 11-14, the trigger mechanism 20 functions in the Lock-In" mode of operation. In this operation, the trigger will maintain the switch in the on" position for continuous operation of the tool if desired. It will be understood that in both assemblies the trigger may be released by the operator for further movement when desired.

TI-IE LOCK-OUT ASSEMBLY The assembly for the Lock-Out" mode of operation is illustrated in FIGS. 1-9. It includes a control pin or button 25 which is movably mounted in a cylindrical casing 26 extending outwardly from the housing 23 at one side thereof. The control pin 25 has a rectangular shank which extends through a rectangular opening 27 in the bottom of the casing 26 and its end extends into an opening 28 formed in the side of the trigger 21. Thus, the control pin is non-rotatable after the assembly has been made.

A coil spring 29 engages with a button 250 affixed to the outer end of the control pin 25 and with the bottom of the casing 26. The spring 29 normally urges the control pin 25 outwardly or to an extended position as shown in FIGS. 2 and 3. A latch or a stop 30 is attached to the inner end of the control pin 25 and extends beyond the pin at one side thereof. In this connection, it will be noted that the rectangular opening 27 in the housing is enlarged at one side to permit the latch 30 to pass through it as the assembly is being made.

In the Lock-Out" assembly, the latch 30 is positioned to extend downwardly or in a position where it will engage with the end of a rib 31 in the trigger 21 which extends to the opening 28 in the trigger. This condition will automatically take place when the control pin 25 is fully extended by the coil spring 29 and the trigger 21 is in its retracted or off position.

In order to depress the trigger 21 and operate the switch 22 to actuate the tool, the control pin 25 must then be depressed by the operator to a position as shown in FIG. 5, where the stop or latch 30 on the control pin 25 is aligned with an interior recess or groove 32 formed in the trigger 21 behind the rib 31. When the latch 30 is in this position, the trigger 21 may then be depressed, as indicated in FIG. 6, to operate the switch 22 and actuate the tool.

When the trigger 21 is released, it is returned to the retracted position, as shown in FIG. 2, by the return spring 24 and in this position, the coil spring 29 automatically moves the control pin 25 outwardly to a position where the latch 30 is in front of the rib 31 and prevents movement of the trigger 21 until the control pin 25 is depressed. Thus, the operator cannot actuate the tool unless he intentionally depresses the control pin 25.

In the illustrated embodiment, the control 25 and the opening 27 in the bottom of the casing 26 are of rectangular configuration to prevent the pin from turning during operation. This insures that the latch 30 will be held in position to engage with the rib 31. As will be described, such positioning will be determined at the time of assembly and to enable the control pin 25 to be properly positioned, it has a round section 33. The round section 33 adjoins the upper end of the square section of the pin and permits rotation of the pin 25 to position the latch as desired when the pin 25 is depressed as the assembly is being made. However, it will be understood that other suitable means may be employed to position the control THE LOCK-IN" ASSEMBLY The Lock-In assembly of the trigger mechanism is illustrated in Figs. 11-14. It will be noted here that the same parts are employed as those for the Lock-Out assembly as described above. However, in this assembly, the stop or latch 30 on the control pin 25 extends along the trigger or toward its forward end. The latch 30 is placed in this position by turning the pin 25 at 90 in a counterclockwise direction relative to the Lock-Out position as shown in FIG. 9. Such positioning can be accomplished at the time of assembly as previously described. In this position, the stop or latch 30 on the control pin 25 is positioned above the rib 31 and does not interfere with movement of the trigger 21. However, the opening 28 in the side of the trigger 21 initially accommodates the latch 30 in either position.

When the trigger 21 is depressed to the position shown in H0. 12. a second recess or cavity 34 in the trigger 21 comes into alignment with the latch 30. Depression of the control pin 25 against the force of the coil spring 29 will then cause the latch 30 to enter the second recess or cavity 34 in the trigger 2]. When the control pin is pushed inwardly to the bottom of the cavity 34, the latch 30 is positioned to the rear of a rib 35 formed on the lower wall of the recess 34. Upon release of the trigger 21, the rib 35 is moved upwardly to a position where the latch 30 will engage with it in return movement of the control pin 25. This holds the trigger in its on position and prevents the control pin 25 and latch 30 from being withdrawn or moved outwardly relative to the trigger.

Under these conditions, continuous operation of the tool will be maintained. The control pin 25 is released by depressing the trigger 21 to release the rib 35 from engagement with the latch 30. This permits the control pin 25 to be moved outwardly by the coil spring 29 and the trigger 21 can then return to its released position, as shown in FIG. 11, to operate the electric switch 22 and interrupt the circuit to the tool.

In assembly of the trigger mechanism, the coil spring 29 is placed on the control pin 25. The control pin 25 and the spring 29 are then inserted in the cylindrical casing 26 with the latch 30 in a position to pass through the opening 27 in the bottom of the housing.

The latch 30 is positioned for the desired mode of operation prior to assembly and with the trigger 21 removed from the housing 23 prior to attachment to the too! as indicated in FIG. 8. This will permit the control pin 25 to be depressed against the coil spring 29 to a position where a round portion 33 of the shank of the control pin is in alignment with the opening 27 in the housing 23. Under this condition, the latch 30 may be positioned for either the Lock-Out or Lock-In" modes of operation as desired. When the control pin 25 is released, the

rectangular section of the control pin enters the rectangular opening 27 in the casing and thus, the control pin 25 cannot be turned after the assembly has been completed.

A modified embodiment of the latch is shown in FIGS. 15 and 16. In this form, the latch 30a has been strengthened by making it thicker to better withstand forces which may be exerted on the trigger. A notch 36 has been provided in the surface of the control pin 25a opposite to the latch 30a. ln the Lock-In mode of assembly, the latch 30a extends upwardly (or is reversed from FIG. 12) and the notch 36 engages with a rib 35a formed on the lower wall of the recess 34 in the trigger and holds the control pin 25a in the recess 34 to prevent return of the trigger 21 to its off position.

Otherwise, the parts and their operation are the same as previously described with corresponding reference numerals being employed.

As mentioned, other means such as a keyway may be employed to prevent the control pin 25 from being turned to change the position of the latch 30 after the assembly has been made.

lt will also be understood that various changes and modifications may be made in the embodiment of the invention illustrated and described herein by those skilled in the art without departing from the spirit or scope of the invention.

What we claim is:

1. In a trigger mechanism for controlling operation of a power tool, the assembly comprising;

a. a housing;

b. a manually operable trigger slidably mounted in the housing for operation of an electrical switch and being reciprocable between a forward position and rearward position in the housing;

c. said trigger having a latch receiving recess formed in one side thereof;

d. a spring biasing said trigger toward said rearward positron;

e. a control pin having an end extending through an opening in the housing and into said recess in a side of the trigger;

f. a latch carried by said end of the pin and extending into said recess;

g. means whereby said latch is positionable in one of two latching positions for latching said trigger and being held in one of said latching positions after assembly and before operation of said trigger; and

h. spring means acting on said control pin;

i. said spring means urging the control pin and the latch outwardly relative to the housing and the recess in the trigger.

2. In a trigger mechanism for controlling operation of a power tool, the assembly as defined in claim 1 which includes:

a. a rib extending along the trigger and having an end terminating at the recess in the trigger;

b. said end of the rib opposing and engaging with the latch in one position thereof;

c. said trigger also contains an open ended groove which extends lengthwise thereof;

d. said groove being located behind the rib and being shaped to receive the latch.

3. In a trigger mechanism for controlling operation of a power tool, the assembly as defined in claim 1 wherein:

a. the trigger contains a second recess formed therein at an upper end thereof; and

b. a latch engaging rib formed on a lower wall of said second recess;

c. said second recess being shaped to receive the latch and being aligned with the control pin and latch when the trigger is in said forward position.

4. ln trigger mechanism for controlling operation of a power tool, the assembly as defined in claim 2 in which:

a. a second coil spring engages with and urges the control pin outwardly with the latch opposing the end of the rib;

b. said second spring permitting the control pin to be depressed for manual movement of the latch out of 0pposing relation to the end of the rib and into alignment with the latchreceiving groove.

5. In a trigger mechanism for controlling operation of a power tool, the assembly as defined in claim 1 wherein:

a. the trigger contains a second recess located at one end of 5 the latch-receiving recess;

b. said second recess being aligned with the control pin and power tool, the combination which comprises:

a hollow housing;

a manually operable trigger slidably mounted in said housing;

said trigger being movable between a forward position and a rearward position and having a latch receiving recess formed in one side thereof;

. a control pin carried by the housing and having an end extending into said latch receiving recess in the trigger;

. a latch carried by said end of the control pin and being located in said latch receiving recess;

means for angularly positioning said latch relative to the trigger and preventing rotation of the control pin to maintain the angular positioning of said latch during operation of the trigger;

. spring means engaging with and urging said control pin outwardly relative to the housing and the trigger; and

. means on the trigger for releasably engaging with the latch on the control pin in different positions thereof relative to the trigger.

7. In a trigger mechanism for controlling operation of a power tool, the combination as defined in claim 6 in which:

the means on the trigger for releasably engaging with the latch includes a rib extending along the trigger and having an end terminating at the latch receiving recess therein;

b. said end of the rib opposing the latch on the control pin and preventing movement of the trigger toward its forward position when the control pin is urged outwardly by the spring means acting thereon; and

c. the trigger contains a groove located behind and extending lengthwise of said rib;

d. said groove being shaped to accommodate the latch in one position thereof to permit movement of the trigger when the control pin is depressed.

8. In a trigger mechanism for controlling operation of a power tool, the combination is defined in claim 6 in which:

a. the trigger has a second recess formed therein;

b. said second recess being aligned with the control pin and latch in the forward position of the trigger; and

c. the means for releasably engaging with the latch includes a rib formed on and projecting from a forward surface of said second recess;

d. said rib engaging with and preventing outward movement of the control pin and latch under the influence of the spring means upon rearward movement of the trigger relative to the housing.

9. In a trigger mechanism for controlling operation of a power tool, the combination as defined in claim 6 wherein:

a. the means for positioning the latch comprises a portion of the control pin having a rectangular configuration and the housing has a rectangular opening through which said rectangular portion of the control pin extends;

b. said control pin also having a portion of circular shape which permits rotation of the pin relative to the housing;

c. said control pin being movable prior to assembly with the trigger to a position where said circular portion is located in the opening in the housing whereby the control pin and latch may be placed in different positions relative to the housing. 

1. In a trigger mechanism for controlling operation of a power tool, the assembly comprising; a. a housing; b. a manually operable trigger slidably mounted in the housing for operation of an electrical switch and being reciprocable between a forward position and rearward position in the housing; c. said trigger having a latch receiving recess formed in one side thereof; d. a spring biasing said trigger toward said rearward position; e. a control pin having an end extending through an opening in the housing and into said recess in a side of the trigger; f. a latch carried by said end of the pin and extending into said recess; g. means whereby said latch is positionable in one of two latching positions for latching said trigger and being held in one of said latching positions after assembly and before operation of said trigger; and h. spring means acting on said control pin; i. said spring means urging the control pin and the latch outwardly relative to the housing and the recess in the trigger.
 2. In a trigger mechanism for controlling operation of a power tool, the assembly as defined in claim 1 which includes: a. a rib extending along the trigger and having an end terminating at the recess in the trigger; b. said end of the rib opposing and engaging with the latch in one position thereof; c. said trigger also contains an open ended groove which extends lengthwise thereof; d. said groove being located behind the rib and being shaped to receive the latch.
 3. In a trigger mechanism for controlling operation of a power tool, the assembly as defined in claim 1 wherein: a. the trigger contains a second recess formed therein at an upper end thereof; and b. a latch engaging rib formed on a lower wall of said second recess; c. said second recess being shaped to receive the latch and being aligned with the control pin and latch when the trigger is in said forward position.
 4. In trigger mechanism for controlling operation of a power tool, the assembly as defined in claim 2 in which: a. a second coil spring engages with and urges the control pin outwardly with the latch opposing the end of the rib; b. said second spring permitting the control pin to be depressed for manual movement of the latch out of opposing relation to the end of the rib and into alignment with the latchreceiving groove.
 5. In a trigger mechanism for controlling operation of a power tool, the assembly as defined in claim 1 wherein: a. the trigger contains a second recess located at one end of the latch-receiving recess; b. said second recess being aligned with the control pin and latch when the trigger is in a depressed position; and c. a latching rib formed on a lower wall of said second recess; d. said latching rib being adapted to engage with the latch on the control pin upon rearward movement of the trigger and when the control pin is depressed therein.
 6. In a trigger mechanism for controlling operation of a power tool, the combination which comprises: a. a hollow housing; b. a manually operable trigger slidably mounted in said housing; c. said trigger being movable between a forward position and a rearward position and having a latch receiving recess formed in one side thereof; d. a control pin carried by the housing and having an end extending into said latch receiving recess in the trigger; e. a latch carried by said end of the control pin and being located in said latch receiving recess; f. means for angularly positioning said latch relative to the trigger and preventing rotation of the control pin to maintain the angular positioning of said latch during operation of the trigger; g. spring means engaging with and urging said control pin outwardly relative to the housing and the trigger; and h. means on the trigger for releasably engaging with the latch on the control pin in different positions thereof relative to the trigger.
 7. In a trigger mechanism for controlling operation of a power tool, the combination as defined in claim 6 in which: a. the means on the trigger for releasably engaging with the latch includes a rib extending along the trigger and having an end terminating at the latch receiving recess therein; b. said end of the rib opposing the latch on the control pin and preventing movement of the trigger toward its forward position when the control pin is urged outwardly by the spring means acting thereon; and c. the trigger contains a groove located behind and extending lengthwise of said rib; d. said groove being shaped to accommodate the latch in one position thereof to permit movement of the trigger when the control pin is depressed.
 8. In a trigger mechanism for controlling operation of a power tool, the combination is defined in claim 6 in which: a. the trigger has a second recess formed therein; b. said second recess being aligned with the control pin and latch in the forward position of the trigger; and c. the means for releasably engaging with the latch includes a rib formed on and projecting from a forward surface of said second recess; d. said rib engaging with and preventing outward movement of the control pin and latch under the influence of the spring means upon rearward movement of the trigger relative to the housing.
 9. In a trigger mechanism for controlling operation of a power tool, the combination as defined in claim 6 wherein: a. the means for positioning the latch comprises a porTion of the control pin having a rectangular configuration and the housing has a rectangular opening through which said rectangular portion of the control pin extends; b. said control pin also having a portion of circular shape which permits rotation of the pin relative to the housing; c. said control pin being movable prior to assembly with the trigger to a position where said circular portion is located in the opening in the housing whereby the control pin and latch may be placed in different positions relative to the housing. 